The invention relates to a resonator and more particularly to a tunable Helmholtz resonator for a vehicle air intake system having a vibratory input to the resonator wall to dynamically adjust the cancellation frequency for time-varying acoustical signals, and at least one of mean resonator volume control, mean resonator neck length control, and mean resonator neck diameter control.
In an internal combustion engine for a vehicle, it is desirable to design an air induction system in which sound energy generation is minimized. Sound energy is generated as fresh air is drawn into the engine. Sound energy is caused by the intake air in the air feed line which creates undesirable intake noise. Resonators of various types such as a Helmholtz type, for example, have been employed to reduce engine intake noise. Such resonators typically-include a single, fixed volume chamber, with a fixed neck length and fixed neck diameter, for dissipating the intake noise.
It would be desirable to produce a variable resonator system which militates against the emission of sound energy caused by the intake air and cancels acoustical signals.
Consistent and consonant with the present invention, a variable resonator system which militates against the emission of sound energy caused by the intake air and cancels acoustical signals, has been discovered.
The continuously variable resonator system comprises:
a housing having a chamber formed therein and a neck portion adapted to provide fluid communication between the chamber and a duct;
an engine speed sensor adapted to sense a speed of an associated engine;
means for controlling at least one of a volume of the chamber, a length of the neck portion, and a diameter of the neck portion, the means for controlling in communication with the engine speed sensor, and the means for controlling at least one of the volume of the chamber, the length of the neck portion, and the diameter of the neck portion responsive to the speed sensed by the engine speed sensor, wherein controlling at least one of the volume of the chamber, the length of the neck portion, and the diameter of the neck portion facilitates attenuation of a first desired frequency of sound entering the resonator;
a noise sensor disposed within the duct;
a vibratory displacement actuator disposed in the chamber of said housing, the vibratory, displacement actuator for creating a vibratory input responsive to noise levels sensed by the noise sensor, wherein the vibratory input cancels a second desired frequency of sound entering the resonator.